Mitosis and body patterning during morphallactic development of palleal buds in ascidians

Kawamura, Kazuo; Nakauchi, Mitsuaki

doi:10.1016/0012-1606(86)90041-2

Cited by 29 publications

(26 citation statements)

References 24 publications

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“…This treatment resulted in the continual morphogenesis. Buds were incubated in filtered seawater at 20°C (8). The antero-posterior body axis is represented by the pharynx (p), endostyle (e), stomach (s), and intestine (i).…”

Section: Animalmentioning

confidence: 99%

Retinoic Acid can Induce a Secondary Axis in Developing Buds of a Colonial Ascidian, Polyandrocarpa misakiensis

1992

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We have examined the effect of retinoic acid (RA) on axial pattern formation during bud development of the ascidian, Polyandrocarpa misakiensis. A bead containing various concentrations of RA was implanted into the distal portion of a bud at a site where morphogenic events do not normally occur. Control buds were implanted with beads containing dimethyl sulfoxide (DMSO), the solvent of RA. No apparent effect was observed in these buds containing beads treated with DMSO. In contrast, beads containing 100 pg/ml of RA could induce ectopic structures in the distal portion of buds in about 30% of the cases. The resulting animals had completely duplicated antero-posterior axes. Histological studies showed that, within two days of RA treatment, atrial epithelial cells situated just beneath the implanted bead became thickened and formed a gut rudiment that resembled the posterior structure of the animal. The effect of RA treatment was dose-dependent. The minimum concentration of RA required to induce a secondary axis was 100 ng/ml. Beads containing 1 mg/ml of RA had a lethal effect on the cells that surrounded the beads. These results are discussed in relation to the role of RA in axis formation and the mechanism by which positional values are specified during normal and aberrant bud development in ascidians.

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Section: Animalmentioning

confidence: 99%

Retinoic Acid can Induce a Secondary Axis in Developing Buds of a Colonial Ascidian, Polyandrocarpa misakiensis

1992

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“…Morphogenesis occurs mainly in the inner multipotent epithelium after the buds are detached from the parent (Fig. 1A, 3) (Kawamura and Nakauchi, 1986;Kawamura and Fujiwara, 1994). In ~1 week, these buds become juvenile zooids (Fig.…”

Section: Introductionmentioning

confidence: 99%

Molecular anatomy of tunicate senescence: reversible function of mitochondrial and nuclear genes associated with budding cycles

et al. 2012

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SUMMARYZooids of the asexual strain of Polyandrocarpa misakiensis have a lifespan of 4-5 months; before dying, they produce many buds, enabling continuation of the strain. This study was designed to investigate the nature of gene inactivation and reactivation during this continuous process of senescence and budding. During senescence, the zooidal epidermis showed acid -galactosidase activity, lost proliferating cell nuclear antigen immunoreactivity and became ultrastructurally worn, indicating that the epidermis is a major tissue affected by the ageing process. Semi-quantitative PCR analysis showed that the genes encoding mitochondrial respiratory chains (MRCs) engaged in decreased transcriptional activity in senescent adults compared with younger adults. The results of in situ hybridization showed that the epidermis dramatically attenuates MRC expression during ageing but restores gene activity when budding commences. During budding and ageing, the nuclear gene Eed (a polycomb group component) was activated and inactivated in a pattern similar to that observed in MRCs. In buds, RNA interference (RNAi) of Eed attenuated Eed transcripts but did not affect the gene expression of pre-activated MRCs. A tunicate humoral factor, TC14-3, could induce Eed, accompanying the reactivation of MRC in adult zooids. When RNAi of Eed and Eed induction were performed simultaneously, zooidal cells and tissues failed to engage in MRC reactivation, indicating the involvement of Eed in MRC activation. Results of this study provide evidence that the mitochondrial gene activities of Polyandrocarpa can be reversed during senescence and budding, suggesting that they are regulated by nuclear polycomb group genes.

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“…4 upper). Budding occurs by the protrusion of the epidermis and the peribranchial epithelium between which mesenchymal cells are located (Kawamura and Nakauchi, 1986). Buds do not have any preexisting organs of the adult, but they renew all tissues and organs including the gonad after separated from the parent.…”

Section: Developmental Dynamicsmentioning

confidence: 99%

Germline cell formation and gonad regeneration in solitary and colonial ascidians

Kawamura

Tiozzo

Manni

et al. 2011

Developmental Dynamics

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The morphology of ascidian gonad is very similar among species. The testis consists of variable number of testicular follicles; the ovary consists of ovarian tubes that are thickened forming the germinal epithelium with stem cells for female germ cells with the exception of botryllid ascidians. Peculiar accessory cells that would be germline in origin accompany the oocytes. Using vasa homologues as a molecular marker, germline precursor cells can be traced back to the embryonic posterior‐most blastomeres and are found in the tail of tailbud embryo in some solitary and colonial ascidians. In Ciona, they are subsequently located in the larval tail, while in colonial botryllid ascidians vasa‐expressing cells become obscure in the tail. Recent evidence suggests that ascidian germ cells can regenerate from cells other than embryonic germline. An ensemble of the embryonic stringency of germ cell lineage and the postembryonic flexibility of gonad formation is discussed. Developmental Dynamics 240:299–308, 2011. © 2011 Wiley‐Liss, Inc.

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Mitosis and body patterning during morphallactic development of palleal buds in ascidians

Cited by 29 publications

References 24 publications

Retinoic Acid can Induce a Secondary Axis in Developing Buds of a Colonial Ascidian, Polyandrocarpa misakiensis

Retinoic Acid can Induce a Secondary Axis in Developing Buds of a Colonial Ascidian, Polyandrocarpa misakiensis

Molecular anatomy of tunicate senescence: reversible function of mitochondrial and nuclear genes associated with budding cycles

Germline cell formation and gonad regeneration in solitary and colonial ascidians

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